JPS627764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rapid charging device for a sealed nickel cadmium storage battery or a small sealed lead acid battery.

Conventionally, there was a method of detecting the battery voltage at the end of charging in order to terminate quick charging of a storage battery, but the detected voltage had to be compensated depending on the battery temperature, which made the circuit complicated, and if the temperature was high, the compensation was insufficient. However, there were disadvantages such as insufficient charging, and the need for a separate terminal in addition to the positive and negative terminals of the battery to detect temperature.

Conventionally, there is also a method of detecting battery temperature, but the rise in temperature of the battery is affected by the heat dissipation conditions around the battery, the ambient temperature, the size of the charging current, etc., and the temperature rise may not be sufficient, especially at low temperatures. However, the thermostat sometimes does not work, and the gas absorption rate of the battery becomes slow, causing gas to be discharged outside the battery and shortening its life. Furthermore, the method of detecting the difference in temperature between the ambient temperature and the battery also has drawbacks such as a complicated circuit and the need for a separate terminal for temperature detection. The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a charging device that can sufficiently and reliably charge a battery quickly.

The configuration of the charging device of this invention is shown in FIG. The charging device consists of a power supply circuit, a quick charge control circuit, and a series circuit of a thermostat. The power supply circuit is for supplying a charging current to the storage battery. The quick charge control circuit has constant voltage and constant current control functions, and is configured to terminate quick charge in response to a signal from the current reduction detection circuit.

The current reduction detection circuit detects that when charging progresses at low temperatures and approaches the end of charging, the terminal voltage of the battery increases.
On the other hand, the quick charge control circuit has a constant voltage control function, and since its output voltage is held down to the charging voltage control value, the charging current of the storage battery gradually decreases, which is used to reduce the charging current to below the specified value. It detects this and sends a signal to the quick charge control circuit to terminate charging. The current reduction detection circuit also detects the current reduction and terminates charging when the charging current becomes zero due to the operation of the thermostat which detects the rising battery temperature at the end of charging and opens the circuit.

A specific example is shown in FIG. The storage battery 35 is made up of 10 nickel cadmium storage batteries with a nominal capacity of 1200 mAh and a nominal voltage of 1.2 V connected in series.

The thermostat 36 is installed around the storage battery to detect the temperature of the storage battery, and has a structure that opens its contacts at 48°C. These storage batteries and a thermostat are integrated into a battery pack C.

Diode 11 conducts when the thermostat contacts are open during discharge. A power supply circuit A is constituted by a power transformer 1, a rectifier circuit 2, and a capacitor 31. Reference numeral B designates a quick charge control circuit, and transistors 3 and 4, SCR 9, resistors 14 and 15, and capacitor 32 constitute a switch circuit. push button 3
Rapid charging is started by pressing 4. In the initial stage of charging, since the charging voltage is less than the charging voltage control value, the charging current is controlled to be a constant current by the transistor 8 and resistors 16 and 17. When the terminal voltage of the storage battery rises at the end of charging at low temperature, the charging voltage is controlled at a constant voltage by the transistor 5, the Zener diode 13, the resistors 18, 20, 21, and the capacitor 33. At the end of charging, when the charging current decreases to the specified value or when the current becomes 0 due to activation of the thermostat due to a rise in battery temperature, transistors 6, 7 and resistors 17, 19, 22, 23, 24, 2
A signal is sent to the SCR 9 from the voltage decrease detection circuit composed of 5, 26, 27, 28, and 29 to turn off the transistors 3 and 4 and terminate charging. The light emitting diode 12 and the resistor 30 are used to indicate that charging is in progress.

Diode 10 is for preventing reverse current from the battery.

The constant voltage control value of this charging device is 16V, the constant current control value is 1.5A, and the current decrease detection point is 0.7A. Figure 3 A shows the state of charging using this charging device.
As shown in B and C, in the case of low temperature (°C) in A, the charging voltage V rises to the constant voltage control value, and at the same time the current decreases to _0.7A , which is the current decrease detection point. finish. The temperature T of the battery has hardly increased.

On the other hand, when the ambient temperature is 20 to 40°C (b), the charging voltage V does not reach the constant voltage control value, and charging continues at a constant current, and charging ends at time _t2 when the battery temperature reaches 48°C. When the ambient temperature in Figure C is 10°C, the charging voltage V momentarily reaches the constant voltage control value, but the charging current I
The current does not decrease to the current decrease detection point and begins to increase as the battery temperature rises, and after the charging voltage falls below the constant voltage control value again, the thermostat operates.
Charging has finished at _t3 .

As described above, the charging device according to the present invention reliably completes charging at low temperatures and performs a sufficient amount of charging in a normal temperature range, so it has great practical effects.

When charging a sealed nickel cadmium storage battery, set the constant current control value to 1CmA to 3CmA (where C is the nominal capacity of the battery), and set the constant voltage control value to 1
1.55~1.65V per cell, current reduction detection point
It is desirable and sufficient to configure the charging device with the battery temperature detection thermostat set at 0.3CmA to 0.8CmA and 40 to 55C to perform the above-mentioned operation.

Furthermore, the device of the present invention is not limited to the embodiment circuit shown in FIG. 2, and modifications such as connecting the battery with three terminals instead of two terminals are obvious to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the storage battery charging device of the present invention, FIG. 2 is a circuit diagram showing a specific embodiment of the device of the present invention, and FIG. FIG. A...Power supply circuit, B...Quick charge control circuit, C
...Battery pack, 35...Storage battery, 36...Thermostat.

Claims (1)

[Scope of Claims] 1. A power supply circuit that supplies charging current to a storage battery, a quick charge control circuit, and a battery temperature detection thermostat that opens when detecting a rise in battery temperature are connected in series, and the quick charge control circuit The circuit has a function to constant-current control the charging current when the charging voltage is below the constant-voltage control value, a function to constant-voltage control the charging voltage when the charging current is below the constant-current control value, and a function to increase the charging voltage at the end of charging. Alternatively, a storage battery charging device characterized by having a function of detecting when the charging current decreases by a certain value or more compared to a constant current control value due to the operation of a thermostat and terminating the rapid charging. 2 Constant current control value from 1C to 3CmA (C is the nominal capacity of the storage battery), constant voltage control value from 1.55 to 1.65V per cell, and current decrease detection point from 0.3C to
The storage battery charging device according to claim 1, which is directed to a sealed nickel cadmium storage battery with an operating temperature of 0.8 CmA and a battery temperature detection thermostat of 40 to 55°C.